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Dive into the research topics where Gerard Olivar Tost is active.

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Featured researches published by Gerard Olivar Tost.


Siam Review | 2008

Bifurcations in Nonsmooth Dynamical Systems

Mario di Bernardo; Chris Budd; Alan R. Champneys; Piotr Kowalczyk; Arne Nordmark; Gerard Olivar Tost; Petri T. Piiroinen

A review is presented of the one-parameter, nonsmooth bifurcations that occur in a variety of continuous-time piecewise-smooth dynamical systems. Motivated by applications, a pragmatic approach is taken to defining a discontinuity-induced bifurcation (DIB) as a nontrivial interaction of a limit set with respect to a codimension-one discontinuity boundary in phase space. Only DIBs that are local are considered, that is, bifurcations involving equilibria or a single point of boundary interaction along a limit cycle for flows. Three classes of systems are considered, involving either state jumps, jumps in the vector field, or jumps in some derivative of the vector field. A rich array of dynamics are revealed, involving the sudden creation or disappearance of attractors, jumps to chaos, bifurcation diagrams with sharp corners, and cascades of period adding. For each kind of bifurcation identified, where possible, a kind of “normal form” or discontinuity mapping (DM) is given, together with a canonical example and an application. The goal is always to explain dynamics that may be observed in simulations of systems which include friction oscillators, impact oscillators, DC-DC converters, and problems in control theory.


Bioresource Technology | 2016

Butanol production from lignocellulose by simultaneous fermentation, saccharification, and pervaporation or vacuum evaporation.

Víctor Hugo Grisales Díaz; Gerard Olivar Tost

Techno-economic study of acetone, butanol and ethanol (ABE) fermentation from lignocellulose was performed. Simultaneous saccharification, fermentation and vacuum evaporation (SFS-V) or pervaporation (SFS-P) were proposed. A kinetic model of metabolic pathways for ABE fermentation with the effect of phenolics and furans in the growth was proposed based on published laboratory results. The processes were optimized in Matlab®. The end ABE purification was carried out by heat-integrated distillation. The objective function of the minimization was the total annualized cost (TAC). Fuel consumption of SFS-P using poly[1-(trimethylsilyl)-1-propyne] membrane was between 13.8 and 19.6% lower than SFS-V. Recovery of furans and phenolics for the hybrid reactors was difficult for its high boiling point. TAC of SFS-P was increased 1.9 times with supplementation of phenolics and furans to 3g/l each one for its high toxicity. Therefore, an additional detoxification method or an efficient pretreatment process will be necessary.


Chaos | 2010

Characterizing chaotic melodies in automatic music composition

Andrés E. Coca; Gerard Olivar Tost; Liang Zhao

In this paper, we initially present an algorithm for automatic composition of melodies using chaotic dynamical systems. Afterward, we characterize chaotic music in a comprehensive way as comprising three perspectives: musical discrimination, dynamical influence on musical features, and musical perception. With respect to the first perspective, the coherence between generated chaotic melodies (continuous as well as discrete chaotic melodies) and a set of classical reference melodies is characterized by statistical descriptors and melodic measures. The significant differences among the three types of melodies are determined by discriminant analysis. Regarding the second perspective, the influence of dynamical features of chaotic attractors, e.g., Lyapunov exponent, Hurst coefficient, and correlation dimension, on melodic features is determined by canonical correlation analysis. The last perspective is related to perception of originality, complexity, and degree of melodiousness (Eulers gradus suavitatis) of chaotic and classical melodies by nonparametric statistical tests.


Archive | 2015

Numerical Simulation Analysis of a Traffic Model

Mónica Mesa Mazo; Johnny Valencia; Gerard Olivar Tost

In this chapter, we present an overview of the piecewise smooth model and simulation of a traffic system, characterized by a single vehicle traveling through a sequence of traffic lights that turn “on” and “off” with a specific frequency and a phase. The model includes three main dynamical modes: accelerated, decelerated, and null state. We show the description of the mathematical modeling used to simulate the system. The simulation was developed under an event-driven strategy and implemented in Matlab. Regarding the numerical analysis, we built a bifurcation diagram where the parameter under variation is the cycle of traffic lights. As a principal result, we evidence the effects of the cycle of traffic light in the dynamical behavior of the system.


Mathematical Problems in Engineering | 2014

A New Robust Controller with Applications to Bioreactors

Alejandro Rincon; Christian Camilo Erazo Ordoñez; Felipe Londoño; Gerard Olivar Tost; Fabiola Angulo

In this work an anaerobic digester is controlled using input-output linearization and Lyapunov-like function methods. It is assumed that model parameters are unknown, time-varying, and bounded, and upper or lower bounds are also unknown. To tackle the effect of input saturation, a state observer is designed. The tracking and observer errors are defined in terms of the noisy measured output instead of ideal output, given by the mathematical model. The design of the observer mechanism and the update laws is based on the Lyapunov-like function technique, whereas the design of the control law is based on the input-output linearization method. In this paper two important properties of the controlled system are proven. First, the observer error converges asymptotically to a residual set whose size is user-defined, and such convergence is not disrupted, neither by the input saturation nor by the parameter uncertainties. Second, when the control input is nonsaturated the tracking error converges to a residual set whose size is user-defined. The model parameter uncertainties are included to prove the convergence of errors. Finally, a numerical example to validate the developed control is presented.


Chemical Engineering and Processing | 2016

Ethanol and isobutanol dehydration by heat-integrated distillation

Víctor Hugo Grisales Díaz; Gerard Olivar Tost


Dyna | 2011

GENERALIZATION OF ZAD STRATEGY: AN APPLICATION TO A DC-DC BUCK CONVERTER

Fabiola Angulo Garcia; Gerard Olivar Tost; Gustavo Adolfo Osorio Londoño


Chemical Engineering and Processing | 2017

Energy efficiency of a new distillation process for isopropanol, butanol, and ethanol (IBE) dehydration

Víctor Hugo Grisales Díaz; Gerard Olivar Tost


Bioprocess and Biosystems Engineering | 2018

Energy efficiency of acetone, butanol, and ethanol (ABE) recovery by heat-integrated distillation

Víctor Hugo Grisales Díaz; Gerard Olivar Tost


Dyna | 2009

ANÀLISIS Y CONTROL DE UN BIORREACTOR ANAEROBIO DE LECHO FIJO DE FLUJO ASCENDENTE

Alejandro Rincon; Fabiola Angulo Garcia; Gerard Olivar Tost

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Fabiola Angulo Garcia

National University of Colombia

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Alejandro Rincon

National University of Colombia

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Fabiola Angulo

National University of Colombia

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Johnny Valencia

National University of Colombia

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Mario di Bernardo

University of Naples Federico II

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